Twilio is another recent entry to the telco mashup scene. Their unique value seems to be the IVR markup language that is far easier to use than VoiceXML.

The more Telco Mashup APIs the better. There are so many telecom providers that act as walled gardens when it comes to programmatic access. BT was among the few to recognize and act by starting 21SDK and more recently purchasing Ribbit. Let the market forces work towards a tipping point.